1. Field of the Invention
In general, the present invention relates to the structure of conductive lead elements that interconnect probes and sensors to medical analysis equipment. The present invention also relates to methods of forming conductive lead elements using printed conductive ink.
2. Prior Art Description
Many medical testing and monitoring systems require that various probes and sensors be attached to the body of a patient. For example, to monitor blood oxygen levels, a pulse oximeter is commonly applied to the tip of the finger. To perform an electrocardiogram, several sensors are attached to the torso and limbs. In each case, the sensor or probe is attached to medical equipment using wire leads. This presents multiple problems.
The primary problem with the wire leads is one of expense. Traditional wire leads contain copper wire, which is expensive. Furthermore, many wire leads have complex structures. For instance, the wire leads that interconnect with a pulse oximeter contains two sets of copper wires that are each shrouded in a conductive sheath to prevent signal interference. The complexity of the wire lead adds significantly to its expense. However, many hospitals routinely use wire leads for only one patient and throw the wire lead away each time a patient is discharged. The replacement costs associated with replacing wire leads costs hospitals, clinics and physicians' offices millions of dollars each year.
The wiring leads for medical equipment, such as electrocardiograms, are so extensive and complex, that they are rarely replaced. Rather, many hospitals, clinics and physicians' offices use disposable probes and repeatedly connect to those probes using the same wiring harnesses. This, of course, presents problems with patient-to-patient contamination. Wiring harnesses come into contact with a patient's skin and clothing. As such, they can be contaminated with bacteria, viruses, blood and/or other bodily fluids.
As a consequence, healthcare providers are required to balance the risks and costs associated with replacing or reusing wire leads. Healthcare providers must either absorb the large expense of replacing or sterilizing wire leads after each use, or they must assume the dangers and complications of potentially cross-contaminating patients by reusing wire leads.
In the prior art, attempts have been made to replace expensive wire leads with less expensive elements, such as printed flexible substrates. Such prior art is exemplified by U.S. Pat. No. 6,006,125 to Kelly, entitled “Universal Electrocardiogram Sensor Positioning Device And Method”. The problems associated with such printed substrates, it that they are printed in one size in the hope that one size fits all. This is clearly not true. An infant is obviously very different in size than a 200 pound man. As such, the premanufactured wiring leads must be produced in a wide variety of sizes and styles to accommodate people of different ages, sizes, shapes and genders. This requires preprinted substrates of many different sizes and lengths to be held in the inventory of a hospital or clinic. The consequence is that large sums of money must be spent on inventory. This negates the cost savings of not using traditional lead wires.
A need therefore exists for new lead elements for medical equipment that can be universally used on all patients, regardless of size, shape, age or gender. A need also exists for such lead elements that are highly reliable, yet inexpensive enough to be replaced after every use. Lastly, a need exists for new lead elements that can be manufactured at a price that is far less expensive than the cost of traditional wire leads or the cost of sanitizing traditional wire leads. These needs are met by the present invention as described and claimed below.